One of my earlier posts describes how to mount your unsupported time machine backup disk within the OSX Installer, allowing you to restore from a Time Machine backup.
well, now I’ve found a guide that tells you how to craft an Avahi service file that will allow you to avoid having to mount the share manually, making it appear to your mac as a standard time capsule
You can find the info on this here: http://www.bootc.net/archives/2010/11/07/apple-time-machine-and-netatalk/